New cold-rolled deep-drawing grades

An unstabilised ultra low carbon steel (12 ppm of C) offers an attractive combination of formability properties like yield strength, elongation, mean r-value and BH-index. The major drawback is its large planar anisotropy. This is attributed to the large grain-size of the hot-rolled product. An increase in the cooling rate (using ultra fast cooling technology) or a decrease in the coiling temperature do not refine the hot-band grain size. However, an optimisation of the cold-rolling and the annealing sequences result in a better balance of the drawing properties. Alloying elements like Cr, B, V, Al. Si or reduction of Mn content exert only a minor influence on the final properties. An addition of Nb (mass contents of 0.01 %) improves the drawability but decreases the BH-index when conventional continuous annealing temperatures are applied.     

Effective properties of composites with embedded piezoelectric fibres

The present work deals with the modelling of 1–3 and 0–3 composites made of piezoceramic fibres embedded in a soft non-piezoelectric matrix. We especially focus on the longitudinal and transversal effective piezoelectric constants as a function of several micromechanical parameters such as the fibre volume fraction or the aspect ratio. Finite-element results, based on the concept of a cell model, are compared with results of analytical approaches. This study is restricted to linear piezoelectricity and quasistatic cases.     

The detection of α‐dicarbonyl compounds in wine by formation of quinoxaline derivatives

A method to determine the most abundant α‐dicarbonyl compounds in wine was developed by reaction with 2,3‐diaminobenzene. Products such as quinoxaline derivatives were detected by high‐performance liquid chromatography (HPLC) or by gas chromatography with a mass‐selective detector (GC–MS) or a thermoionic detector (GC–NPD). HPLC and detection with a spectrophotometer (313 nm) were used for routine quantitative analysis of wines. The method is sensitive, linear and has good repeatability. Diacetyl, pentane‐2,3‐dione, glyoxal and methylglyoxal were quantified in a single run; these compounds are always encountered in wines, but levels vary with different types of wine and also during fermentation and maturation processes. A new dicarbonyl compound, phenylglyoxal, was found in wine. The evolution of dicarbonyl compounds during fermentation is reported in this paper. © 2000 Society of Chemical Industry     

Macromolecular Engineering via Carbocationic Polymerization: Branched Structures,Block Copolymers and Nanostructures

This article features macromolecular engineering via carbocationic polymerization, the focus of research of the recently established Macromolecular Engineering Research Centre (MERC) at the University of Western Ontario. The fundamental philosophy of MERC is interdisciplinary research with a strong industrial orientation, while emphasizing the quest for fundamental understanding of polymerization processes and polymer structure‐property relationships. First, a brief overview of living polymerizations in general, and living carbocationic polymerizations in particular will be given. This latter technique is of interest because some monomers (e. g., isobutylene) can be polymerized by cationic techniques only, to yield polymers with unique properties (e. g., polyisobutylene with superior chemical and oxidative stability, low permeability and high damping). This will be followed by an overview of our research strategy and a summary of our latest results. These include the development of a fiber‐optic mid‐FTIR method for the real‐time monitoring of low temperature polymerization processes, the discovery that selected epoxides initiate effectively the living carbocationic polymerization of isobutylene, fundamental studies into the mechanism and kinetics of living carbocationic polymerization, and the design and synthesis of various polymer architectures (e. g., branched homo‐ and block copolymers) with improved properties and nanostructured phase morphologies.     

Arbitrary branched and intersecting cracks with the extended finite element method

Extensions of a new technique for the finite element modelling of cracks with multiple branches, multiple holes and cracks emanating from holes are presented. This extended finite element method (X‐FEM) allows the representation of crack discontinuities and voids independently of the mesh. A standard displacement‐based approximation is enriched by incorporating discontinuous fields through a partition of unity method. A methodology that constructs the enriched approximation based on the interaction of the discontinuous geometric features with the mesh is developed. Computation of the stress intensity factors (SIF) in different examples involving branched and intersecting cracks as well as cracks emanating from holes are presented to demonstrate the accuracy and the robustness of the proposed technique. Copyright © 2000 John Wiley & Sons, Ltd.     

On modelling and rendering ocean scenes

This paper is devoted to ocean images. First we propose a complete geometrical model accounting for refraction, diffraction, reflection, transmission and multiwave trains. Then we describe a specific algorithm for the rendering of coastal scenes. Copyright © 2000 John Wiley & Sons, Ltd.     

Aggregation behaviour of monosulfonated telechelic ionomers

The behaviour of monosulfonated telechelic polystyrene with various molar masses and different counterions has been investigated using static and dynamic light scattering. For concentrations above the critical micelle concentration, free unimers associate to form well‐defined star‐shaped micelles. The number of polystyrene chains per micelle (n_ag) is independent of the concentration and the type of counterion; n_ag decreases with decreasing molar mass of the polystyrene and increasing polarity of the solvent. The micelles behave like covalently bonded star polystyrene from a structural, dynamic and thermodynamic point of view. © 2000 Society of Chemical Industry     

Power Consumption of a Rushton Turbine Mixing Viscous Newtonian and Shear-thinning Fluids: Comparison between Experimental and Numerical Results

A fluid dynamics software package (Fluent) was used to calculate the local velocities in a standard tank fitted with a Rushton turbine. We defined the local average shear rate γ˙¯ as a user variable. The power was computed from the values of γ˙ with a user subroutine. The influence of the rheological behaviour of the fluid was investigated: the shape factor K_p for a Newtonian fluid, and in the case of a shear-thinning fluid Metzner and Otto′s concept was used to determine the effective shear rate γ˙_e · γ˙_e verified the classical relation: γ˙_e = K_s·N. The influence of position and stirring speed on the local average shear rate γ˙¯ was also studied. As expected, higher values were obtained near the turbine. At a fixed position, γ˙¯ was found to be proportional to the stirring speed N. The power values obtained by numerical procedures were compared to experimental results: the Fluent software yielded results in excellent agreement with experimental findings. The calculation of local parameters such as the local average shear rate γ˙¯ as well as global characteristic shape factors demonstrate the validity of Fluent software in the laminar range.     

Optimization of Advanced Live-Cell Imaging through Red/Near-Infrared Dye Labeling and Fluorescence Lifetime-Based Strategies

Fluorescence microscopy is essential for a detailed understanding of cellular processes; however, live-cell preservation during imaging is a matter of debate. In this study, we proposed a guide to optimize advanced light microscopy approaches by reducing light exposure through fluorescence lifetime (τ) exploitation of red/near-infrared dyes. Firstly, we characterized key instrumental elements which revealed that red/near-infrared laser lines with an 86x (Numerical Aperture (NA) = 1.2, water immersion) objective allowed high transmission of fluorescence signals, low irradiance and super-resolution. As a combination of two technologies, i.e., vacuum tubes (e.g., photomultiplier) and semiconductor microelectronics (e.g., avalanche photodiode), type S, X and R of hybrid detectors (HyD-S, HyD-X and HyD-R) were particularly adapted for red/near-infrared photon counting and τ separation. Secondly, we tested and compared lifetime-based imaging including coarse τ separation for confocal microscopy, fitting and phasor plot analysis for fluorescence lifetime microscopy (FLIM), and lifetimes weighting for enhanced stimulated emission depletion (STED) nanoscopy, in light of red/near-infrared multiplexing. Mainly, we showed that the choice of appropriate imaging approach may depend on fluorochrome number, together with their spectral/lifetime characteristics and STED compatibility. Photon-counting mode and sensitivity of HyDs together with phasor plot analysis of fluorescence lifetimes enabled the flexible and fast imaging of multi-labeled living H28 cells. Therefore, a combination of red/near-infrared dyes labeling with lifetime-based strategies offers new perspectives for live-cell imaging by enhancing sample preservation through acquisition time and light exposure reduction.